1. Technical Field
The present invention relates to a method and an apparatus for redundancy of a wireless communication network, and more particularly, to a method for efficiently constructing a resource block in a structure for redundancy of a railway wireless communication network of which the reliability and stability need to be secured and a method and an apparatus for redundancy of a wireless communication network capable of improving a wireless signal quality.
2. Description of the Related Art
At present, instead of the existing train control system in which wayside devices are connected to each other in a wired manner, a safe and simple radio frequency communication based train control (CBTC) system which newly constructs control sharing of a wayside device and an onboard device has been developed and practically used in some countries. In the future, with the tendency of technology development, the radio frequency communication based train control and communication system is likely to be more widely applied to a railroad.
The CBTC system is equipped in the wayside device and the onboard device board and provides continuous communication between the wayside device and the onboard device to secure stability of a train service. Further, comparing with the traditional wired based signal control system, the CBTC system may shorten a headway to increase a transport capacity and may provide data communication between a train and a central control system to increase operation efficiency of a train and to optimize stability and convenience of a railroad.
In Europe, the radio frequency CBTC system uses a GSM-R which is allocated with some of frequencies in a GSM band for a railway and in some countries including USA, the radio frequency CBTC system uses the IEEE 802.11 standard of a 2.4 GHz band industrial scientific medical (ISM) band for a train control. The wireless communication of the CBTC system which is used in the national ShinBundang line, and the like uses an ISM band of 2.4 GHz and the CTBC system using the ISM band is planned to be additionally installed in the future.
However, the radio frequency communication based train control (RF-CBTC) system using the ISM band is difficult to continuously secure performance due to interference, crosstalk, and the like in terms of characteristics of the 2.4 GHz band and therefore the train service may stop. To cope with the above problem, it is necessary to secure a railway only frequency. Considering the 2.4 GHz band which is used in the country, operational uncertainty may occur due to the interference and the crosstalk. Therefore, to stably operate the train service, it is very necessary to secure the railway only frequency for safely and pleasantly operating a railway traffic service in spite of a difficulty in a frequency allocation procedure and period for a stable train operation.
Recently, however, it is difficult to be allocated with many frequency domains for a railway when wireless data are explosively increased. In particular, it is necessary to construct redundancy of a railway network and a cell coverage to immediately cope with emergency situations. In conclusion, in the existing LTE system, a two-fold frequency is required to remove frequency interference between neighboring base station transceiver subsystems for a railway communication network. In this case, to implement the redundancy of the train control signal with a low transmission amount, a frequency two times as large as the existing required amount is required and therefore frequency efficiency may be suddenly reduced. Meanwhile, Korean Patent Publication No. 2009-0004165, etc., discloses only the redundancy to increase a capacity of transmission rate and therefore there is a need for a technology to increase efficiency and stability of a frequency.